Registers and grilles are used to cover the openings onto living areas of air supply and return ducts of central and other heating, cooling and ventilating systems. They perform a beautification function by covering the duct opening and by concealing the rough finish around the hole cut in the wall, ceiling or floor to serve the duct. They also perform a flow control function by regulating and directing the flow of air to or from the duct.
Conventional registers of the type to which the present invention relates have frame, duct inset and flow control portions. The frame portion consists of a margin or border that surrounds the point of entry of the duct opening onto the living area and serves to provide an aesthetically pleasing transition surface which may be slightly rounded to provide a channel into which an insulation strip of foam tape or other material can be placed. The duct inset or box portion of the register leads back into the duct at right angle to the inner edges of the frame portion and serves as an interface between the frame and the duct. The frame and duct inset portions are generally rectangular and shaped to match the cross-section of the duct. The inset portion of the register is typically dimensioned to fit snuggly and concentrically within the duct channel, though sometimes an adapter is interposed (such as when a rectangular register is joined to a round duct). The frame portion extends perpendicularly to the duct central axis, and is positioned substantially flush with the wall or other living surface boundary onto which the duct opens.
The flow control portion of the register is comprised of one or more layers of vanes or blades which extend in louver or shutter fashion across the register opening defined by the facing inside surfaces of the frame and duct inset portions of the register. The blades may be fixed or movable. In a typical arrangement, a horizontal array of fixed blades is positioned ahead of a vertical array of movable blades; the fixed blades serving to deflect the air and the movable blades acting like damper vanes to permit movement from register open to register closed positions, with intermediate positions regulating the amount of air flow.
The terms "registers" and "grilles" are sometimes used interchangeably. Insofar as such structures are distinguishable, grilles tend to lack, or at least have greatly reduced, inset portions and are often used in places, such as at the air return of a residential central heating/air conditioning system, where the opening at the living area is smaller than the size of the adjoining air shaft or duct. The present invention has application to both registers and grilles. However, to avoid needless repetition, the term "register" will be used throughout with the understanding that, except where the context requires otherwise, the term "register" encompasses both registers and grilles.
A common form of prior art register construction utilizes a single piece of material for the frame. Rearwardly folding tabs provided at the insides of the frame serve for attachment of a separately formed duct inset portion. In another form of construction, the duct inset portion is provided with leading end portions that are bent outwardly at right angles for attachment to a single or multiple part frame portion. Vanes are typically firmly attached directly to the inside walls of the inset portion, or fitted for pivoting on end pins into corresponding holes in the inset. Other forms exist which provide connection between frame, duct inset and vane portions of registers in various other complex ways.
The manufacture and assembly of prior art registers requires many steps and is in many cases labor intensive. Different sizes and styles of registers for the same cross-sectional duct configuration require different processes. As assembly of the useable register often involves rigid connection of frame and duct inset pieces by means of rivets and other permanent connections, the registers are bulky in shipment and storage. Where register parts are put together by screws or similar threaded fasteners, original shipment bulk is reduced but tedious assembly labor is required by the distributor or end user.